1. Field of the Invention
The invention relates to image capture lens modules, and more particularly to, high performance wafer-level packaged image capture lens modules and wafer level packaged image capture devices.
2. Description of the Related Art
Digital cameras utilizing high-resolution electronic imaging sensors typically require high resolution optical components such as image capture lens modules. The design and manufacturing of camera modules for portable electronic products is extremely challenging. Some pervasive factors include: high production volume, constant price erosion, size limitations and changing performance and functionality requirements.
The number of image capture lenses on a digital camera module that focus a scene onto an imager can be as few as one for a digital camera module, or as many as four for a digital camera module with mega pixel resolution. Usually, the lenses are plastic, to lower costs. However, higher quality digital cameras sometime use glass for the first lens because of its superior optical properties.
FIG. 1 is a schematic view illustrating a configuration of a conventional imaging lens. Referring to FIG. 1, a conventional imaging lens module 100 includes a first lens element 110, field stops 130, and a second lens element 120 received in a barrier body 140. The barrier body 140 and a flange 160 are formed together as a barrier. The flange 160 has a frustum hole 170 serves as an aperture stop. The first and second lens elements 110 and 120 include aspheric surfaces. The opaque area of field stops 130 is ring-like in shape. Spacers 150 are disposed at the rear end of the lens module. Conventional imaging capture lens modules adopt concentric plastic or metal ring field stops 130 stacked between the first and second lens elements 110 and 120. By using material characteristics of the plastic or metal field stop 130, scattered light and stray-light can be eliminated to improve image quality. A typical field stop 130 is formed with a concentric ring shape due to fabrication and lens module assembly compatibility.
There are, however, some problems for the conventional image capture lens module, such as inner light scattering, stray-light effect and ghost images. Ghost images are secondary images formed by stray-light reflected twice from lens, filter, window, and image sensor array surfaces. Particularly, the inner circular area of the plastic or metal field stop is larger than the effective sensing area of the image plane, resulting in multiple light reflections inside of the lens module. These multiple light reflections may result in ghost images and stray-light. Accordingly, wafer level packaged lens modules having no stray-light and reduced ghost images are desired for a digital camera.